Photographic treating bath



Paglia Aug w PHOTOGRAPHIC TREATING BATH Heinrich Ulrich and Karl Saurwein, Ludwigshaien-on-the-Rhine, Paul Goldacker, Dessau- Haideburg, and Georg L. Maiser, Dessau, Ger! many, assignors, by mesne assignments, to Agfa Ansco Corporation, Binghamton, N. Y.', a corporation of Delaware No Drawing. Application June 23, 1937, Serial No. 149,836. In Germany June 25, 1936 7 Claims.

The present invention relates to photographic treating baths and more particularly to photographic treating baths in which there is added to the bath an aliphatic nitrogeneous polycarboxylic acid or a water-soluble salt thereof, particularly an alkali metal salt.

Photographic treating baths;for instance alkaline developing baths or neutral baths for reducing, bleaching or intensifying, are generally prepared by diluting with water the commercial concentrated solution or by dissolving in water the powdered chemical in question. In either case, if the local water supply is used precipitation of the lime salts occurs which forms a milky turbidity in o the baths, whereby observation of the progress of the photographic operation is impeded. Frequently the lime salt settles on the photographic layer and produces so-called water spots in the removal of which the photographic layer may easily be damaged. For avoiding this trouble it has been proposed that photographic treating baths should be prepared with distilled water. However, this is not frequently at hand and its use becomes costly when large quantities of treating baths are required, as for instance in the production of high class prints, for instance carbro-, bromoil-, gum-bichromate and pigment prints.

It is an object of the present invention to provide additions to photographic treating baths by which the precipitation of insoluble calcium salts is prevented.

A further object is to provide chemicals for photographic purposes which readily dissolve in water and do not cause precipitation of lime therefrom.

A further object is to provide photographic treating baths which contain aliphatic nitrogenous polycarboxylic acid or water-soluble salts therefrom.

A further object is to provide a substitute for alkali metal carbonates in photographic baths by adding an alkali metal salt of a nitrogenous polycarboxylic acid to said bath. v

Further objects will be apparent from the detailed specification'following hereafter.

Itmust be said that quite generally the allphatic nitrogenous polycarboxylic acids have the effect of preventing precipitation of lime in photographic treating baths. Without limiting the invention tothe specific examples a few' of those acids especially suitable for this purpose are enumerated:

Trimethylamine-tricarboi ylic acid omooon Tetramethyl-dia.minoethane-tetracarboxylic acid NCHr-C]I7-N H00'00m CHaCOOH and di omega. omega methylamino diethylamine-dicarboxylic acid carboxylic acids may at the same time be used as substitutes for alkali metal carbonates in photographic baths. The use of the alkali metal salts defined instead of-alkali metal carbonate has not only the .advantage of preventing precipitation of lime, but a special advantage resides in the fact that the formation of carbon dioxide 4 does not occur when transportinga photographic material from an alkaline bath of this kind into an acid after-treating bath. It is known that a photographic material developed in one of the usual developers which contain sodium carbonate or potassium carbonatev may by after-treatment in an acid stop-bath show defects owing to the formation of gaseous carbon dioxide in the photographic layer. These defects are avoided by using alkali metal salts of aliphatic nitrogenous polycarboxylic acids instead of sodium or potassium carbonate. Developingsolutions in which alkali metal carbonate is substituted by an aliphatic nitrogenous polycarboxylic acid are for instance l methylamino 4 hydroxybenzenesulfate grams 4 Sodium sulflte cryst do 40 The sodium salt of tetramethyldiaminoethane-tetracarbo'xylic acid grams 20 Potassium bromide do 0.4 Water cc 1000 1-methylamino-4-hydroxybenzene-suliate grams" 1 Hydroquinone do 6 Sodium sulfate cryst do 52 The sodium salt of trimethylamino-tricarboxylic acid do 30 Potassium bromide do 1 Water cc 1000 What We claim is:

1. A composition of matter comprising at least one substance suitable for treating a photographic material and a member selected from the class consisting of aliphatic amino-polycarboxylic acids containing at least one amino group, in each amino group present at most one hydrogen atom being directly attached to' the amino nitrogen and water-soluble salts of said aliphatic aminopolycarboxylic acids.

2. A photographic treating bath comprising an aqueous solution containing at least one substance suitable for treating a photographic material and a member selected from the class consisting of aliphatic amino-polycarboxylic acids containing at least one amino group, in each amino group present at most one hydrogen atom being directly attached to the amino nitrogen and water-soluble salts of said aliphatic aminopolycarboxylic acids.

3. A photographic treating bath comprising an aqueous solution containing at least one substance suitable for treating a photographic material and about 0.05 to about 1 percent of a member selected from the class consisting of aliphatic amino-polycarboxylic acids containing at least one amino group, in each amino group present at most one hydrogen atom being directly attached to the amino nitrogen and watersoluble salts of said aliphatic amino-polycarboxylic acids.

4. An alkaline photographic treating bath comprising an aqueous solution containing at least one substance suitable for treating a photographic material and an alkali metal salt of an aliphatic amino-polycarboxylic acid containing at least one amino group, in each amino group present at most one hydrogen atom being directly attached to the amino nitrogen.

5. A photographic treating bath comprising an aqueous solution containing at least one substance suitable for treating a photographic material and the sodium salt of tetramethyldiamino-ethane-tetracarboxylic acid.

6. A photographic treating bath comprising an aqueous solution containing at least one substance suitable ior treating a photographic material and the sodium salt of trimethylaminotricarboxylic acid.

7. The process of preventing the precipitation of salts causing the hardness of water from photographic treating baths made up with hard water and containing at least one substance suitable for treating a photographic material, which comprises adding to said baths a substance selected from the class consisting of aliphatic am-ino-polycarboxylic acids containing at least one amino group, in each amino group present at most one hydrogen atom being directly attached to the amino nitrogen and the watersoluble salts of said aliphatic amino-polycarboxylic acids.

HEINRICH ULRICH. KARL SAURWEIN.

PAUL GOLDACKER. GEORG L. MAISER. 

